The present invention is directed generally to the monitoring and control art and more particularly to a novel and improved monitoring and control system for a mobile material distribution apparatus.
Generally speaking, mobile material distribution devices or apparatus include on-the-road and off-the-road spreader and sprayer apparatus. Such apparatus generally require control systems for controlling the rate of distribution of material by means of various control valves or other control members. Examples of such material distribution apparatus are agricultural fertilizer sprayers and/or spreaders, as well as machines used in agriculture for distributing various insecticides, herbicides and other material. Similarly, over-the-road vehicles may be utilized to distribute insecticide or herbicide materials along highways, or to distribute dust control or binder materials for some road surfaces, or for various ice control products.
It will be appreciated that each of the forgoing applications requires a control arrangement to control the flow or supply of material fed to a distribution device for carrying out the actual spreading or spraying of material on the surface to be treated. Examples of such a distribution device are a spray bar having one or more nozzles for spraying liquid materials and a rotary broadcast-type spreader for distributing granular materials. Generally, the control arrangement may employ a control valve in line with the supply of liquid to be sprayed by the nozzles, or in return line if desired, to control the pressure and/or flow to the nozzles. Alternatively, the control valve may be used as pilot-type of valve in a hydraulic or other control system for regulating the speed of one or more pumps or conveyor drive motors in the case of granular materials. Other systems may use other electrical or electromechanical control members for controlling the rate of delivery of a liquid or a granular material to the appropriate spray bar or broadcast spreader for distribution.
In addition to providing for such control functions, it is also desirable to monitor and display the distribution rate of material from time to time to assure proper operation of the apparatus to an operator. In addition, it is often desirable in such systems to additionally monitor other factors such as the remaining quantity of liquid or granular material remaining in a hopper or supply tank mounted on the vehicle, or the pressure and/or flow rate at one or more supply lines in the case of liquid sprayer apparatus. It is also desirable to provide for periodic selectable automatic flushing or cleansing of the system in a liquid distributor system.
The prior art has proposed a variety of monitoring and/or control systems for such material distribution apparatus. Examples of such systems may be found in Wilder et al. U.S. Pat. No. 3,344,933, Oligschlaeger U.S. Pat. No. 3,877,645, Steffen U.S. Pat. No. 4,052,003 and Bachman et al. U.S. Pat. No. 4,392,611.
We now propose to provide a "universal" or "programmable" type of monitoring system which is capable of being provided either as original equipment or retro-fitted to any of a variety of different mobile material distribution apparatus. However, such a universally usable monitoring and control system would require a great deal of flexibility. That is, the system must have the ability to accommodate a variety of different types of ground speed sensors, flow meters, pressure meters and other input or monitoring devices, in order to provide both accurate and useful displays of apparatus operation as well as to provide accurate and reliable control of material distribution rate.
For example, many types of ground sensor apparatus are known, from relatively simply mechanical or electromechanical tachometers to relatively sophisticated radar-based. "Doppler" speed detection systems. Similarly, the control of granular-type spreaders often requires monitoring and control of a drive component for a conveyor or like material delivery structure. Such control would require a similar rotational speed detector or "tachometer", which may be of various mechanical or electromechanical or even electromagnetic types, and moreover may be placed at any of a variety of locations in the drive system of a given apparatus. That is, such a "pick-up" device might be placed directly adjacent a rotating member of the conveyor itself, elsewhere back in the drive system, such as adjacent some conveniently-accessible gear or shaft or other rotating drive or transmission member. Similarly, the flow of material to nozzles in a liquid sprayer system amy be detected as a function of pressure in the spray bar, pressure in a return line, or alternatively, by metering the flow in a delivery conduit or line to the spray bar. Moreover, the choice of the type, number and spacing of nozzles for liquid sprayers must also be taken into account in order to properly monitor, display and control the distribution rate of material.
As a further matter, such a universal monitoring and control system must further be adaptable to monitoring and display in terms of either English or metric units as desired by a particular operator. Such a system must further be capable of calibration over a relatively wide range of application rates for use in distributing various materials at differing rates for given purposes. Moreover, many materials require that the density or weight per unit volume of material also be taken into account in determining and controlling the distribution rate. Such a system must also be adaptable to a plurality of types and numbers of nozzles, and/or broadcast spreader devices, as well as to varying effective widths of coverage achieved thereby, in order to properly monitor and control the distribution rate of material on a per unit area basis. Additionally, such systems must be capable of setting in certain predetermined maximum and minimum desired operating limits, as well as various alarm limits, so that the operator may have an observable alarm or warning when operation fails to fall within such limits. Such warning may be accompanied by automatic shut-down of one or more components of the apparatus as well, if desired.
In accordance with the invention, a monitoring and control system is provided for a mobile material distribution apparatus wherein the rate of material distribution per unit of area varies as a predetermined function of the ground speed of the mobile apparatus and of the rate of operation of variable rate delivery means for delivering material at a controllable rate to material distribution means for distributing the material along the path of travel of the mobile apparatus; said monitoring and control system comprising: ground speed sensor means for developing a ground speed signal corresponding to the ground speed of the mobile apparatus and delivery rate sensor means for developing a delivery rate signal corresponding to a rate of delivery of material by said variable rate delivery means; said monitoring and control system including monitoring and control circuit means responsive to said ground speed signal and to said delivery rate signal for developing a control signal for controlling the operation of said variable rate delivery means to achieve and maintain a desired rate of distribution of material along the path of travel of the mobile distribution apparatus, said monitoring and control circuit means further comprising processing means responsive to said ground speed and delivery rate signals for producing said control signals and memory means for storing data and instructions for enabling said processing means to respond to delivery rate signals from each of a plurality of different types of delivery rate sensor means.